Stock pusher

ABSTRACT

A stock pusher has a frame for operatively mounting on the bed of a punch press. A lever is pivotally mounted on the frame, there being a first region on the lever which operatively engages stock and pushes the same against a reaction surface. A second region on the lever is operatively engaged by the ram of the press to pivot the lever and cause the stock to be pushed against the reaction surface. The distances between the pivot point and the first and second regions are such as to provide a mechanical advantage with respect to pushing the stock. The stock pusher is of one-piece construction so as to be quickly and easily mounted on the press bed.

United States Patent [191 Charnota et al.

[ Apr. 16, 1974 STOCK PUSHER [76] Inventors: Steven Charnota, 4945 N.

Normandy Ave., Chicago, 111. 60656; Arnold F. Wolf, 551 1 Warren Ave., Morton Grove, 111. 60053 [22] Filed: Nov. 6, 1972 [21] Appl. No.: 303,825

[52] US. Cl 2l4/1.3, 83/387, 83/419 [51] Int. Cl B26d 7/16 [58] Field of Search ..2214/1.1, 1.2, 1.3, 1.5, '214/1.6, 1.7; 83/419, 421, 467, 387, 389

[5 6] References Cited UNITED STATES PATENTS 2,629,443 2/1953 Girardello 83/387 X 3,400,838 9/1968 Leis et al7 2,964,004 12/1960 Carper 3,516,316 6/1970 Cooper 83/419 2,542,213 2/1951 Schwarcz 83/389 X Primary Examiner-Frank E. Werner Attorney, Agent, or Firm-Prangley, Dithmar, Vogel,

Sandler & Stotland 5 7] ABSTRACT A stock pusher has a frame for operatively mounting on the bed of a punch press. A lever is pivotally mounted on the frame, there being a first region on the lever which operatively engages stock and pushes the same against a reaction surface. A second region on the lever is operatively engaged by the ram of the press to pivot the lever and cause the stock to be pushed against the reaction surface. The distances between the pivot point and the first and second regions are such as to provide. a mechanical advantage with respect to pushing the stock. The stock pusher is of one-piece construction so as to be quickly and easily mounted on the press bed.

5 Claims, 6 Drawing Figures PATENTEDAPR 16 1914 3,804,265

sum 11 0F 2 FIG. I

. STOCK PUSHER It is an object of the present invention to provide a stock pusher which, through a mechanical advantage, is capable of pushing stock against a reaction surface in a punch press with a minimum force applied to the pusher.

Another object is to provide a stock pusher which is of essentially one-piece construction, so that it can be easily and'rapidly attached to the bed of a punch press.

Still another object is to provide a stock pusher that applies no pressure to the stock while it is being advanced in the press, but can be adjusted to apply pressure to the stock for any selected interval during the punching cycle.

Yet another object is to provide a stock pusher in which the force applied to the stock can be modified according to specific needs.

A further object is to provide a stock pusher which is inexpensive and lightweight.

A still further object is to provide a stock pusher which can easily be mounted on existing dies.

In summary, there is provided a stock pusher for use in a press having first and second press members at least one of which is movable toward and away from the other, and a reaction surface against which stock is pushed while being worked in the press, said stock pusher comprising a frame for mounting on the first press member, a lever pivotally mounted on the frame about a pivot point and having first and second regions, the first region being located for operatively engaging the stock to push the stock against the reaction surface, thesecond region being located for operative engagement by the second press member to pivot the lever in a given direction to cause the first region to bear against the stock, the distance between the pivot point and the first region being less than the distance between the pivot point and the second region so as to attain a mechanical advantage with respect to pushing the stock. I

Preferably, there is provided a compression spring between the second press member and the second region of the lever to cause resilient engagement between the lever and the stock.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification when taken in connection with the accompanying drawings, in which:

FIG. 1 is a top plan view of a die set with the upper die member and elements mounted thereon having been removed, stock pusher incorporating therein the features of the present invention being mounted on the lower die member;

FIG. 2 is a view in vertical section taken along the I line 2-2 of FIG. ,1; and also illustrating in phantom the bed and ram of a press in which the die setis mounted;

FIG. 3 is a view in vertical section similar to the vertical section of FIG. 2, but on an enlarged scale with portions of the stock pusher being sectioned to illustrate the condition thereof when the ram is in its down position;

FIG. 4 is an end view of the stock pusher shown in FIG. 3;

FIG. 5 is a view like FIG. 3, but illustrating the condition of the stock pusher during the descent of the punch and just prior to the time it strikes the stock; and

FIG. 6 is a view in horizontal section on an enlarged scale taken along the line 6-6 of FIG. 4.

Turning now to the drawings, and more particularly to FIGS. 1 and 2 thereof, there is illustrated in phantom a press 10, the press 10 including a fixed bed 11 and a vertically-reciprocable ram 12. The particular form of press illustrated is a piercing press and is used to punch holes in stock 15. The stock 15 is illustrated as being a continuous strip of metal in which a hole is punched followed by advancement of the stock 15 a predetermined distance, either manually or by a mechanism (not shown), whereupon another hole is punched, etc. The mechanism to be described insures that the stock 15 assumes a predetermined lateral position (up and down as viewed in FIG. 1) to insure that the hole will be formed in the precise location desired each time the stock 15 is advanced. While the press 10 is of the piercing variety, it should be understood that the invention to be described has utility in presses performing a wide variety of functions.

Mounted on the press 10 is a die set 20 that includes a die shoe 21 which carries at its rear a pair of upstanding guide posts 22. The die shoe 21 has means (not shown), such as bolts or the like, for mounting to the bed 11 of the press 10. Also furnished as part of the die set 20 is a punch holder 23 which has a pair of bushings 24 respectively receiving the guide posts 22. The punch holder 23 also has means (not shown), such as bolts or the like, which are used for mounting onto the ram 12. A punch pad 25 is mounted on the underside of the punch holder 13, which punch pad 25, in turn, carries a punch 26. A die block 27 is mounted on the die shoe 21, which die block has a die block opening 28 in vertical alignment with the punch 26. A stripper 29 has a stripper opening30 therethrough aligned with the die block opening 28 and the punch 26. A rail 31 is provided between the die block 27 and the stripper 29 at the rear thereof. The front of the rail 31 defines a'reaction surface'32 as will be described. A space between the die block 27 and the stripper 29, approximately centrally thereof, defines a passageway 33, through which passes the stock 15. FIG. 2 illustrates the punch 26 in its down position wherein it has removed a slug 16 from the stock 15 to form a hole therein. The stripper 29 operates in the usual manner to prevent the stock 15 from being lifted by the punch 26 as it is being withdrawn or raised. After the punch 26 is withdrawn, a mechanism (not shown) will advance the stock 15 a predetermined amount, whereupon the punch 26 will descend to remove another slug 16 from the stock 15. Alternatively, the stock 15 may be advanced manually.

back length relative to the width of the stock 15 and the Y rail 31, so that the front portion of the pusher plate 34 protrudes slightly from the front of the die block 27 and the stripper 29, as shown. The rear end of the stripper 29 engages the front edge of the stock 15. Force applied to the front edge of the pusher plate 34, in turn, pushes the stock rearwardly against the reaction surface 32 of the rail 31. It is important that such force be exerted on the pusher plate 34 each time the punch 26 is punching a slug 16 from the stock 15, in order that the resulting hole be precisely located relative to the width of stock. Also, it is necessary that the pusher plate 34 be released when the punch 26 moves up-' wardly, to enable the stock 15 to be advanced without front-to-back restraint. To this end, there is provided a stock pusher 40.

Turning nowto FIGS. 3 to 6, the details of construction of the stock pusher 40 will be described. The stock pusher 40 comprises a frame consisting of two'frame sections 42, one being the mirror image of the other. Each frame section 42 has a side wall 43 and a U- shaped channel 44 extending upwardly therefrom. The U-shaped channels 44 of the two frame sections 42 together define a guide 45 which is generally square in transverse cross section (see FIG. 6). A screw 46 is threadably engaged in a hole in the bight portion of the U-shaped channel 44 in one of the frame sections 42, the shank 47 of the screw 46 protruding inwardly. Each frame section 42 has an outwardly-directed flange extendingsubstantially normal to the associated side wall 43, which flanges 48 have openings therethrough for receiving bolts 49 to attach the stock pusher 40 to the die shoe 21. A bottom plate 50 is secured to the bottom of the flanges 48, which bottom plate 50 has openings for receiving therethrough the bolts 49. A-spacer 51 may be provided to space the stock pusher 40 from the die shoe 21.,

The stock pusher 40 also comprises a lever 60 in the form of a plate-like body or block which has a region 61a on one edge 61 to engage the front edge of the pusher plate 34. On the edge 62 (which is normal to the edge 61) is a second region 62a which is operatively engaged by the ram 12 in a manner to be described presently. A rivet 63 passes through a bore in the lever 60 near the corner at which the two edges 61 and 62 intersect, and through suitably-aligned openings respectively in the side wall 43 of the frame sections 42. The rivet 63 functions as a pivot point about whichthe lever 60 pivots. 'In' the edge 64 which is parallel to the edge 62 there is formed a recess 65 which receives one end of a spring 66, the other end of which spring engages the upper surface of the bottom plate 50. The spring 66 resiliently pivots the lever 60 clockwise about the rivet 63, as shown in FIG. 5, so that the region 61a is out of engagement with the pusher plate 34.

The stock pusher 40 also comprises a spring retainer 70 which has a top wall 71 that is substantially square and four elongated depending side walls 72, which spring retainer 70 isin the form of an elongated housing. The spring retainer 70 fits within the guide 45 so as to be slidable or reciprocable therein. A spring 74 is provided in the spring retainer 70, one end of the spring bearing against the inner surface of the top wall 71 of the spring retainer 70 and the other end of the spring bearing against the region 62a on the lever 60. A threaded bolt is threadably engaged in a hole in the top wall 71, the shank of which bolt extends downwardly into the spring retainer through the spring 74. The head 76 of the bolt 75 is engageable by the punch holder 23. Finally there is provided a nut 77 which, when tightened, locks the bolt 75 in the position selected.

When the ram 12 is in its uppermost position, the punch 26 may be in the position shown in FIG. 5, in which case the front end of the punch holder will just contact the bolt head 76. Alternatively, the bolt 75 may be adjusted, so that the head 76 does not contact the punch holder 23 in the raised position of the ram. In either event, the spring 74 is in its uncompressed state, exerting no force on the lever 60. The spring 66 urges the lever 60 clockwise to prevent the region 61a from contacting the front edge of the pusher plate 34. In such condition, the stock 15 may be advanced either mechanically or manually, in view of the space between the stock 15 and the reaction surface 32.

Turning to FIG. 3, as the punch 26 descends, it pushes on the head 76 to compress the spring 74 and provide a force at the region 62a of the lever 60, which increases as the punch 26 descends. Eventually, the force exerted by the spring 74 will overcome the force exerted by the spring 66, whereupon the lever 60 will be pivoted about the rivet 63 counterclockwise to cause the region 61a of the lever 60 to engage the pusher plate 34. The rear edge of the plate 34, in turn, pushes the stock 15 against the reaction surface 32. The stock 15 is'now exactly and precisely positioned, and the punch 26 continues its descent to punch a slug 16 from the stock 15 and thereby form a hole therein.

, The punch holder 23 then ascends, whereby the force exerted by the spring 74 at the region 62a decreases until the force exerted by the spring 66 is sufficient to cause the lever 60 again. to pivot clockwise, thereby disengaging. the region 61a from the pusher plate 34. The stock 15 may be advanced, starting a new cycle.

The distance between the rivet 63 and the region 62a is substantially greater than the distance-between the rivet 63 and the region 610 (in the embodiment shown, about two times). Thus a mechanical advantage is achieved. Specifically, the force furnished at the region 62a need only be half the force required at the front of the pusher plate 34. Assuming that about 100 pounds of force at the front of the pusher plate 34 is required in order to hold thestock 15 securely against the reaction surface 32 while the punch 26 operates thereon, only '50 pounds of force need beprovided at the region 62a. There is essentially a series connection between the punch holder 23 and the region 62a, which series connection consists of the bolt 75, the spring retainer and the spring 74. Thus, the spring 74 must be capable of sustaining the entire force exerted at the region 62a. By virtue of the mechanical advantage and the resulting need for less force at the region 62a, a smaller and less expensive spring 74 need be provided. Also, because of the series connection just described, all the force exerted on the lever 60 is transmitted via the spring 74 which provides a resilient yet firm force, which increases as the ram descends.

The height at which the stock pusher 40 is operative can be adjusted by controlling the height of the bolt which protrudes from'the spring retainer 70. Thus, if the bolt 75 is threaded out, then the punch holder 23 will strike the head 76 earlier in its stroke; whereas, if the bolt 75 is threaded into the spring retainer 70, the punch holder 23 will not strike the head 76 until later in the stroke. Whatever position for the bolt 75 is finally selected, a nut 77 is provided to retain the bolt 75 in the selected position. This adjustability feature not only enables adjustment according to the spread of the die member of the die set used, but also enables control of the duration of each cycle for which the stock pusher 40 is operative. Thus, for example, it may be desirable to have the punch and the stock pusher 40 operativeto hold the stock 15 for say 20 percent of the cycle of 25 percent of the cycle. By virtue of the adjustment just described, such control is feasible.

The attachment of the stock pusher 40 is easily accomplished, since it is a one-piece or integral unit. In other words, all that need be done is to attach the stock pusher 40 to the die shoe 21 by the use of the bolts 49. No connection or modification to the punch holder 23 need be performed. Such simple attachment operation would result in substantial savings in installation of a stock pusher. The stock pusher 40 is also relatively inexpensive, since the frame, consisting of the frame sections 42, is constructed of sheet metal parts.

The amount of force applied to the stock pusher 40 is in large part controlled by the coefficient of elasticity of the spring 74. If the stock is very thin, it would be desirable to reduce the force applied to the pusher plate 34, which is easily and quickly accomplished by replacing the spring 74 with a spring having a lesser coefficient of elasticity.

While a preferred embodiment of the invention has been shown and described for illustrative purposes, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. A stock pusher for use in a press having first and second press members at least one of which is movable toward and away from the other, and a reaction surface against which stock is pushed while being worked in the press, said stock pusher comprising a frame for mounting on the first press member and including an elongated guide, a body pivotally mounted on said frame about a pivot point and having first and second regions, said first region being located for operatively engaging the stock to push the stock against the reaction surface, an elongated housing slidably carried by said guide and located to be operatively engaged by the second press member, and a compression spring in said housing and being located to engage said lever at said second region, whereby operative engagement of said housing by the second press member resiliently pivots said lever in a direction to cause said first region resiliently to bear against the stock.

2. The stock pusher set forth in claim 1, wherein said frame and said housing are substantially square in lateral cross section.

3. The stock pusher set forth in claim 1, and further comprising an adjustable threaded bolt threadably engaging a hole provided in said housing and being located to be engaged by the second press member to move said housing so as to compress said spring and pivot said lever.

4. The stock pusher-set forth in claim 3, and further comprising means for locking said bolt in a selected position.

5. The stock pusher set forth in claim 1, wherein said compression spring is loosely held in said housing and is therefore readily replaceable. 

1. A stock pusher for use in a press having first and second press members at least one of which is movable toward and away from the other, and a reaction surface against which stock is pushed while being worked in the press, said stock pusher comprising a frame for mounting on the first press member and including an elongated guide, a body pivotally mounted on said frame about a pivot point and having first and second regions, said first region being located for operatively engaging the stock to push the stock against the reaction surface, an elongated housing slidably carried by said guide and located to be operatively engaged by the second press member, and a compression spring in said housing and being located to engage said lever at said second region, whereby operative engagement of said housing by the second press member resiliently pivots said lever in a direction to cause said first region resiliently to bear against the stock.
 2. The stock pusher set forth in claim 1, wherein said frame and said housing are substantially square in lateral cross section.
 3. The stock pusher set forth in claim 1, and further comprising an adjustable threaded bolt threadably engaging a hole provided in said housing and being located to be engaged by the second press member to move said housing so as to compress said spring and pivot said lever.
 4. The stock pusher set forth in claim 3, and further comprising means for locking said bolt in a selected position.
 5. The stock pusher set forth in claim 1, wherein said compression spring is loosely held in said housing and is therefore readily replaceable. 